Nuclear power plant steam generation

The nuclear power plants that generate electrical power, for example, like those that burn fossil fuel, function by heating water into steam in order to turn the turbines that produce electricity. The fuel consists of uranium oxide (commonly known as yellowcake) processed into solid ceramic pellets and packaged into long vertical tubes that are inserted into reactors to produce a controlled fissile chain reaction. Either pressure or cold water is utilized to control reactor heat and the intensity of the reaction. 

In a nuclear power plant, fission generates heat that is used to boil water and create steam. The steam then turns a turbine on a generator to produce electricity. Note that the water carrying heat from the reactor core is contained within separate pipes and does not come into direct contact with the steam that drives the turbines. 

Due to the many problems concerning steam generators of nuclear power plants over the last decades, we developed our own inspection equipment and services. Next to this main activity, we provide inspections for nuclear power plants components such as thimbles, guide carts and baffle bolts. 

It has developed a real time method to compare successive non-destructive inspections of the steam generator tubes in nuclear power plants. Each tube provides a safety barrier between the primary and secondary coolant circuits. Each steam generator contains several thousands of tubes whose structural integrity must be ensured through the lifetime of the plant, Therefore, Laborelec performs extensive nondestructive tests after each plant outage. 

Fig. 1. Pressurized water reactor (PWR) coolant system having U-tube steam generators typical of the 3—4 loops in nuclear power plants. PWR plants having once-through steam generators contain two reactor coolant pump-steam generator loops. CVCS = chemical and volume-control system.

The largest consumers of water in the United States are thermal power plants (eg, steam and nuclear power plants) and the iron and steel, pulp and paper, petroleum refining, and food-processing industries. They consume >60% of the total industrial water requirements (see also Power generation Wastes, industrial). 

The energy from nuclear fission is released mainly as kinetic energy of the new, smaller nuclei and neutrons that are produced. This kinetic energy is essentially heat, which is used to boil water to generate steam that turns turbines to drive electrical generators. In a nuclear power plant, the electrical generation area is essentially the same as in a plant that burns fossil fuels to boil the water. 

A nuclear power plant generates electricity in a manner similar to a fossil fuel plant. The fundamental difference is the source of heat to create the steam that turns the turbine-generator. A fossil plant relies on the combustion of natural resources (coal, oil) to create steam. A nuclear reactor creates steam with the heat produced from a controlled chain reaction of nuclear fission (the splitting of atoms). 

In a nuclear power plant, heat must be transferred from the core to the turbines without any transfer of matter. This is because fission and neutron capture generate lethal radioactive products that cannot be allowed to escape from the core. A heat-transfer fluid such as liquid sodium metal flows around the core, absorbing the heat produced by nuclear fission. This hot fluid then flows through a steam generator, where its heat energy is used to vaporize... 

Nuclear power plants generate electricity in much the same way fossil fuel power plants do. Water is heated to create steam that can be used to turn electricity-generating fur bines. The fundamental difference between these two types of power pi ants i s th e fuel used to h eat th e water. A fossil fuel plant burns fossil fuel, such as coal or petroleum, but a nuclear plant, such as the one shown in this chapter s opening photograph, uses the heat created by nuclear fission to heat the water. 

FIGURE 22.9 A nuclear power plant. Heat produced in the reactor core is transferred by coolant circulating in a closed loop to a steam generator, and the steam then drives a turbine to generate electricity. 

Most of the worlds electricity is generated with steam turbines. The major difference between power plants is the type of fuel used to boil the water and change it from liquid to gas. Nuclear power plants use nuclear energy to boil the water in steam turbines, while fossil fuel plants burn fossil fuels, such as coal, to boil the water in steam turbines. 

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